There is a camera known in the related art that automatically tracks a moving subject while photographing the subject and executes focus detection or exposure calculation accordingly. The camera in the related art tracks a target object determined to indicate a high level of correlation through pattern matching based upon an image stored therein to be used as a reference for subject tracking (see, for instance, patent reference literature 1).    Patent document 1: Japanese Laid Open Patent Publication No. 2006-58431